The weird thing is that I don't think Lighting centralizes anything at all.
All it does is provide a way for 2 people to send BTC back and forth off chain.
It's intrinsically very decentralized and permissionless given two consenting parties.
The real thing centralizing Bitcoin is the refusal to increase the blocksize to match technological inflation. That shit is rolling down hill into Lightning with the expectation that Lightning will fix it, even though it can't.
It's also interesting that you mention XMR... because I'm not sure that XMR is any more scalable than BTC is. In fact logic would dictate that zero-knowledge proofs are a lot of extra steps so it may even be less scalable. We won't know for sure until people are actually using it. Serai DEX could be the breakthrough everyone has been waiting for.
The issue is the idea of scaling lightning to be a global payment network... from what I have read, which is not a tonne... it will effectively need to use custodial wallets, and we are back to banking 2.0.
I saw a meme (and I am sure you did too) that said "BTC is the CBDC"
If lightning ever does scale (with large custodial lightning wallets) to that size (which is doubtful) privacy is a thing of the past.
Lightning as it is now, is niche and pseudo private. If you have a use for it... great.
BTC would scale with larger blocks, but alas, we will never see that on the current BTC chain... the XMR people all seem confident (that is until they get the traffic, your point is very valid). BCH says it can scale well beyond VISA/MC with sub penny fees (believe it when I see it).